Statistical analysis shows pattern consistent with pre-industrial temperature swings, study concludes
From McGill University’s Shaun Lovejoy
Statistical analysis of average global temperatures between 1998 and 2013 shows that the slowdown in global warming during this period is consistent with natural variations in temperature, according to research by McGill University physics professor Shaun Lovejoy.
In a paper published this month in Geophysical Research Letters, Lovejoy concludes that a natural cooling fluctuation during this period largely masked the warming effects of a continued increase in man-made emissions of carbon dioxide and other greenhouse gases.
The new study applies a statistical methodology developed by the McGill researcher in a previous paper, published in April in the journal Climate Dynamics. The earlier study — which used pre-industrial temperature proxies to analyze historical climate patterns — ruled out, with more than 99% certainty, the possibility that global warming in the industrial era is just a natural fluctuation in the earth’s climate.
In his new paper, Lovejoy applies the same approach to the 15-year period after 1998, during which globally averaged temperatures remained high by historical standards, but were somewhat below most predictions generated by the complex computer models used by scientists to estimate the effects of greenhouse-gas emissions.
The deceleration in rising temperatures during this 15-year period is sometimes referred to as a “pause” or “hiatus” in global warming, and has raised questions about why the rate of surface warming on Earth has been markedly slower than in previous decades. Since levels of greenhouse gases have continued to rise throughout the period, some skeptics have argued that the recent pattern undercuts the theory that global warming in the industrial era has been caused largely by man-made emissions from the burning of fossil fuels.
Lovejoy’s new study concludes that there has been a natural cooling fluctuation of about 0.28 to 0.37 degrees Celsius since 1998 — a pattern that is in line with variations that occur historically every 20 to 50 years, according to the analysis. “We find many examples of these variations in pre-industrial temperature reconstructions” based on proxies such as tree rings, ice cores, and lake sediment, Lovejoy says. “Being based on climate records, this approach avoids any biases that might affect the sophisticated computer models that are commonly used for understanding global warming.”
What’s more, the cooling effect observed between 1998 and 2013 “exactly follows a slightly larger pre-pause warming event, from 1992 to 1998,” so that the natural cooling during the “pause” is no more than a return to the longer term natural variability, Lovejoy concludes. “The pause thus has a convincing statistical explanation.”
The methodology developed in Lovejoy’s two recent papers could also be used by researchers to help analyze precipitation trends and regional climate variability and to develop new stochastic methods of climate forecasting, he adds.
—————————-
The paper:
“Return periods of global climate fluctuations and the pause”, Shaun Lovejoy, Geophysical Research Letters, published online July 14, 2014. DOI: 10.1002/2014GL060478
Abstract
An approach complementary to General Circulation Models (GCMs), using the anthropogenic CO2 radiative forcing as a linear surrogate for all anthropogenic forcings [Lovejoy, 2014], was recently developed for quantifying human impacts. Using preindustrial multiproxy series and scaling arguments, the probabilities of natural fluctuations at time lags up to 125 years were determined. The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence. In this paper, this method is extended to the determination of event return times. Over the period 1880–2013, the largest 32 year event is expected to be 0.47 K, effectively explaining the postwar cooling (amplitude 0.42–0.47 K). Similarly, the “pause” since 1998 (0.28–0.37 K) has a return period of 20–50 years (not so unusual). It is nearly cancelled by the pre-pause warming event (1992–1998, return period 30–40 years); the pause is no more than natural variability.
Preprint paper here:
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http://armstrongeconomics.com/2014/07/21/global-warming-crowd-now-argue-it-is-cycles-that-mask-the-warming-trend/
“The Global Warming crowd is now desperately trying to counter-act the data that says they are quite frankly about as credible as the old Y2K crowd back in 2000. The data have clearly shown that they have lied, manipulated, and outright carried out a major fraud upon society. They argue that man has altered the entire planet in just a few decades which is like focusing on a 7 day reaction in a bear market and declaring it’s really a bull market. The theory is totally unsound simply from a realistic research perspective.
The fact that surface temperatures have not warmed over the past 17 years showing that their climate models are unreliable, is now amazingly being refuted with quick new research led by James Risbey. In just a matter of weeks, he is leading the charge demonstrating his clearly predisposed bias. Risbey now excuses their nonsense of models that have overestimated global warming with a slapped together study published in Nature Climate Change asserting that their models actually generate good estimates of recent and past trends provided they also took into account natural variability known as El Nino-La Nina phases in the Pacific. OOPS! Cycles?
Risbey stated: “The climate is simply variable on short time scales but that variability is superimposed on an unmistakable long-term warming trend.”
Risbey claims that the skeptics have lately relied on a naturally cool phase of the global cycle to fan doubts about climate change, the fact temperature records continue to fall even during a La-Nina dominated period is notable. Yet his argument reveals his own mistake – HELLO THERE ARE CYCLES. He boldly states that the temperature rising from the build-up of greenhouse gases in the atmosphere “is beginning to overwhelm the natural variability on even shorter decadal time scales”. Quite frankly, he lacks any historical evidence long-term to support any such conclusion. As long as people like this put out bogus research, they have a job. Without global warming theory, sorry, they need to find something else to scare people with to get a pay check for shallow research.
As long as this type of bogus research unfolds, government can justify taxing energy.”
Martin Armstrong
Natural cooling variation from exactly what?
Quantify it with something!
Read this quote in the conclusion of the paper…. Oh the pain》
“This approach can profitably be extended; to other fields – notably
precipitation – and to the spatial domain – to regional variability. Finally, it is
possible to make stochastic climate forecasts using multifractal models whose
strengths and weaknesses will complement the GCM’s. These applications promise
to enrich both our understanding of the climate of its models. “
Steve says:
July 21, 2014 at 5:19 pm
what’s up with all the latest hoopla this week about 2013 being the hottest on record?
I saw something about 2013 being from 2nd to 6th warmest. However it ranked 10th on RSS and 8th on Hadcrut4.
Historical standards? What historical standards?
If it’s “historical” standards established by satellite measurements then, yes, since those measurements only starts in 1979 and don’t provide much of a history.
But if it’s historical standards established by the thermometer record, then, yes, because: (1) the data has been repeatedly adjusted; (2) the thermometer was invented during the depths of the Little Ice Age; and (3) the Little Ice Age is recent in comparison to the earth.
If it’s historical standards established by the paleoclimate proxy record, then NO, not even close. Ten of thousands of 15-year periods have been warmer in the Holocene, to say nothing of millennia during the Eemian integlacial, the interglacials which preceded it during the Pleistocene, previously in the Pliocene, Miocene, Oligocene, Eocene & Paleocene Epochs, most if not all of the Mesozoic Era & most of the Paleozoic, with rare exceptions.
(Btw, most of the language used above was been borrowed from another WUWT commenter about a year ago. I’m sorry for not remembering your name.)
noting snark
The ready availability of cheap computing power to third rate academics is a dangerous thing.
Felix says:
July 21, 2014 at 5:36 pm
The combined average temperature over global land and ocean surfaces for June 2014 was the highest on record for the month, at 0.72°C
GISS has June 2014 at 0.62 at the third highest, and way below its 1998 value of 0.75.
Werner,
The temps could not have been 0.X oC average world wide.
Felix is trying to get by, deliberately or not, with bs. Don’t let the climate obsessed set the agenda.
This is all about anomalies, not actual temperatures.
Derived through huge interpolative processes that are not proven to add to accuracy, much less deliver anything of any significance. Think of the dynamic range of temps around the planet and then consider is 0.XoC could ever be significant in the first place.
The climate obsessed have set the agenda for decades and all we have to show for it is billions upon billions wasted, a lot useless data and government policies that are even less useful than normal. Challenge their agendas, challenge their assumptions.
Lenny says:
July 21, 2014 at 6:29 pm
I’m new to this but, if the warmists recognize a pause how can the Guardian claim 352 consecutive months of above average temperatures. Would that not refute a pause?
No, and to illustrate this, a 50 year old man who stopped growing at age 20 could say he was above his average height for the last 360 months. That does not mean he continued to grow for the last 30 years.
Felix, it’s the “highest” temps now because we just had/are having a solar “max” peak this summer, and temps for 17+ years have been riding on top of a literal heatwave that crested to current levels after the 1997/98 El Nino, after climbing during an extended period where the Earth retained extra heat from higher solar activity.
If this is a surprise to you, don’t feel bad, many people here are also finding out for the first time how the Sun dictates temps with it’s activity cycles. Solar variation is natural too.
Look at your source http://www.ncdc.noaa.gov/sotc/global/2014/6 , where they say “The combined global land and ocean average surface temperature for the January–June period (year-to-date) was 0.67°C (1.21°F) above the 20th century average of 13.5°C (56.3°F), tying with 2002 as the third warmest such period on record.
The high temp record in 2002 followed the 2nd peak (of the solar max) of SC23 in late 2001. It is not a coincidence that the warm temp records occurred at or after solar maxes in SC23 and SC24.
Steven Mosher
“noting snark”
Is an anagram for what?
hunter says:
July 21, 2014 at 8:15 pm
Felix is trying to get by, deliberately or not, with bs.
Felix is quoting NOAA that just came out with their June numbers here:
http://www.ncdc.noaa.gov/sotc/global/
However so far, no other global data set that is out for June agrees with NOAA. That includes GISS, RSS and UAH.
My head hurts and I need an Excedrin. Natural variability can cause the pause but not the previous warming trend? Oh and sophisticated computer models, none of which have been correct? Now I need a shot of scotch to go with that Excedrin.
“Lies, Damn Lies, and Statistics.” Analyze few decades of information, and claim that it’s a robust enough statistical universe to reject, completely, any explanation for warming outside of their own claims—that it’s primarily mankind’s miniscule contribution to this trace gas, which is responsible for every catastrophe from extreme heat to extreme droughts to taifuns to the extreme cold of the past Winter with the Dread “Polar Vortex.”
I take great exception to this person’s use of the term “denier”, for starters. But let’s ask, since he seems to think he’s invented a new branch of infallible statistical analysis which can determine that the last few decades of warming can only be attributable to man—when no one even knows all the sinks and sources of this trace gas he’s so consumed with—what does his analysis say of the fact that nearly every GCM today has an increasing divergence from all measured surface temperature records: satellite, surface station, or radiosonde? And that this increasing divergence is that they are all uniformly HIGHER than measured temperatures? What is the statistical possibility of THAT, if they’re all so accurate?
The justifications… “…the tight relationship between global economic activity and emissions…” Confirmed by statistical analysis of the residuals. GIGO, anybody?
Look, aside from the obvious, that correlation is not causation, there’s this inconvenient fact: it’s technology which has mitigated a great deal of pollution already. It’s clear to anyone who reads history that between them, London, New York and Pittsburgh probably put out as much smog combined as all of Asia today, prior to 1950. And now they do not. Why? Because they don’t use wood and coal burning stoves to cook anymore. Why not? Electricity, natural gas, oil, and more efficient burning of fossil fuels. Oh, and refrigeration, oddly enough (smoking, as a method of commercial food preservation, is mostly a delicacy now, yes? And that’s not the only impact—but I don’t want to get too far afield). The primary reason the developing world is so polluted and polluting isn’t merely that the developed nations are exporting their pollution, or imperialism, or any other claim—it’s because they don’t have the affluence that comes from that “economic actcivity” to afford the efficient methods of energy generation which would allow them to reduce their CO2 output, among other things they generate.
But ok, Lovejoy claims to have proven that the warming cannot be natural, and though he hasn’t proven it’s anthropogenic, gee, what else might it be?
Leaving aside the fact that most of the skeptical community is asking the same question (sans the prejudice that it MUST be man’s fault–and yet, I agree with them to this extent: it IS Mann’s fault…well, with the help of Algore and Schneider et al…), let’s just assume, for the moment, that we know the earth is 4.3 billion years old. Just how accurate are we trying to be about this mythical critter, “Global Mean Temperature”, the mean surface temp? As our host has proven with a project a few years back, not only do we not have terribly accurate surface temperature monitoring stations due to poor locations and poor station upkeep, but we don’t have high granularity over the surface even over land, to say nothing of the surface over water, to calculate a mean, and the satellite record is far too short to provide more than the mean over the last three decades.
But mean over what duration? Between sundown and sunup would produce a sort of misleading curve, right? Sunup to Sundown? I bet the Alarmists would love that!
Just since the Industrial Revolution? That choice seems to have some justification, except that we can prove that the temperatures were still rising from the depths of the Little Ice Age.
Since the Winsconsin Glaciation? Perhaps the one previous?
Why not use the mean since as far back as we’ve got proxies? If we look at a timescale a wee bit longer than just the period during the last 5 million years or so when glaciation occurs pretty regularly every 100,000 years or so with a 15-20,000 year interglacial, we can see that the earth has been in a glaciation for roughly 2.67million years, really, and from a more general perspective, even longer: 34 million years (that being roughly how long there’s been an Antarctic ice cap, the Arctic cap being in place for roughly the last 27 million). 34 Million. Long time, right? Lemme put it in a different perspective: one THOUSANDTH of the time the earth has existed.
And for nearly 80% of the other 99.99% of it’s existence, the mean temperature had been what, about 22 degrees celcius? Even just going back to the and of pre-Cambrian times, 600Mya, only 120 million years or so were under 22 degrees C mean temp, and 100 million years of that between the mid-Devonian and the beginning of the Triassic where, as the CO2 content of the atmosphere dropped, temperatures skyrocketed from ice age to over 22 degrees C (skyrocketed…over a few million years).
Seems to me that it could get a LOT warmer than it is right now, and STILL be natural, because compared to 99.9999% of the earth’s existence, it’s been a lot warmer than it is currently.
And where was the statistical analysis of this in Lovejoy’s paper? It wasn’t, because no one really can; we’re talking about reconstructions from proxies, right (oh wait, what was he saying about “multiproxy temperatures?)?
So we don’t know that much about the past, except broadly speaking, but the past might have a very profound affect on our present and future if as some suspect, the earth appears to be warming because in reality it’s simply returning to an equilibrium that it has maintained, more or less, for most of it’s existence (because hey, if we can’t explain why CO2 could be 7000 ppmv at 22 Degrees C in the Cambrian, and 1000 ppmv and 22 Degrees in the Jurassic, how can we say that 400 ppmv and rising is a big deal now, right?).
But no, Lovejoy has a better idea: analyze a few seconds of time with his new, super-wham-o-dyne statistical method and you too can predict the Atlantic Basin hurricane season 100 years from now with 99.999% confidence!
If I sound a little, well, skeptical, it’s because on a quick review of his paper, it appears to me he’s torturing the math to arrive at a self-serving conclusion. He even quotes AR5 and their description of what 95% confidence means—without ever acknowledging that there’s no math behind that scale, only politics.
I’m not an expert by any means, but I have a very hard time believing that an analysis of such a short period, when contrasted with the entire existence of the earth, is not the very worst sort of cherry-picking.
“Also sprack Lovejoy, thus moot it be!”
Sorry, I ain’t buyin’ it.
Sparks says:
July 21, 2014 at 8:26 pm
Steven Mosher
“noting snark”
Is an anagram for what?
________________________________
I think he just got the acronym spelled wrong. 😉
http://en.wikipedia.org/wiki/Spatial-numerical_association_of_response_codes
I have a question someone can help with.
Steven Goddard pulls news archives from 50-80 years ago. It’s quite interesting to read. Is it possible to pull more recent peer reviewed published climate science papers? Say from 1990 – 2010? I’m aware of Google Scholar.
It’d be fun and informative to develop a “This day in climate science history” blog.
“The hypothesis that the industrial epoch warming was a giant natural fluctuation was rejected with 99.9% confidence.”
They’re even more confident than they thought.
Does this exact matching / masking work with view to the actual measurements, or does it work based on the first, second or third round of adjustments to the data? And how does this need to be read after a further round of adjustments?
I am sure it says that somewhere in the paper, I am only wondering whether one would have ended up with the same conclusion, or even idea, based on the temp record from, say, two years ago before the recent adjustments were applied. Just asking because to get a flat line, you need a rather exact match for the cancelling effect.
I don’t know about his methodology, but I like his conclusions.
If cyclical natural variability slows temp growth in a way that no model does, it’s clear that temps by 2010 will be lower than models suggest…perhaps lower than ANY model suggests, since to my knowledge, none of them include this ameliorating cycle. Therefore, climate sensitivity probably below the IPCC’s lowest guess at 1.6 (if I remember right). No C in the AGW. Cheaper to adapt than mitigate.
Let’s welcome Lovejoy to the world of Climate Skepticism.
Rdcii:
You assume that the climate sensitivity is a constant. This is an unwarranted assumption.
======================================================================
I beg to differ. It tells us that they know a hell of a lot less about AGW than they think they do but they are well versed in the art of CYA.
I’m lost – does this mean all the heat didn’t go into the deep deep oceans because there wasn’t any heating after all ?
damn – and I thought the science was settled !!
dbstealey says:
July 21, 2014 at 6:35 pm
Lenny,
The Guardian is feeding the public a load of crap. Satellite data — the most accurate of all — shows that global warming stopped many years ago.
In fact, the planet is slightly cooling. [See the green trend line in the chart.]
What a load of rubbish, if you actually knew anything about the null hypothesis and variance you’d know that that data is not able to show that the planet is cooling.
This seems pretty clear to me.
Lovejoy’s new study concludes that if the sophisticated climate models are excluded the historical climate records (data) show that the pause and previous warming have been natural cooling & warming fluctuations.
That leaves the alarmists & AGW rather stranded with only their sophisticated conjecture from climate models and without any data to claim it cannot be natural.
That’s a travesty.
Isn’t that exactly what Watts,Tisdale, McIntire et al have been saying for years?
Who ya gonna believe?
Phil.?
Or your lyin’ eyes?
Lol… for years most, if not all of the warming was meant to be caused by man…so now we have a pause, and natural variability accounts for it?
Doesn’t that imply that at least 50% of warming was natural variability? Is this guy a skeptic?